1. Field of the Invention
The present invention relates generally to vehicle suspension springs, and more particularly to generally longitudinal, non-convolute automotive beam springs used to provide spring action in two planes.
2. Description of the Related Art
Previous automotive suspension systems using leaf springs relied on substantial elastic deformation in only one plane. Substantial inboard-outboard deformation of the spring was controlled by substantially higher spring rate stiffness in these planes created by wide leaf spring cross sections. Inboard-outboard deformation was typically not desired in these configurations since they were mainly paired with conventional beam axles which spanned the width of the vehicle and whose weight was completely unsprung by the suspension that is the entire weight of the axle was attached to the spring and not dependent on the chassis.
The conventional leaf spring designs are excellent for beam axle applications. Conventional Leaf springs are not suited to independent suspension systems however. These independent suspension systems are characterized by axles with a differential attached to the chassis and use articulated halfshafts to transmit torque to the unsprung wheel ends. The wheel ends in an independent suspension system travel in an arc controlled by a control arm. Since these independently suspended wheel ends travel in an arc rather than straight up and down (requiring two planes of deformation), leaf springs with only one plane of elastic deformation are not suitable. Currently, these independent suspension systems rely on coil springs and control arms to provide a suitable suspension. Coil springs mount differently on a chassis than do leaf springs and so the two systems are not interchangeable on a common chassis. In addition, control arms for coil spring suspensions are often very heavy and rely on multiple attachment points and expensive bushings to provide appropriate suspension characteristics. Coil springs and their control arms thus introduce added complexity and cost to an automobile over a conventional leaf spring design.
It would be desirable, therefore, to provide a spring which mounts to a vehicle like a leaf spring yet provides the multiple-plane elastic deformation of a coil spring.
The present invention overcomes the disadvantages of the prior art approaches by providing a beam spring, which substantially elastically deforms in two planes.
It is an object and advantage of this invention to provide a beam spring with a longitudinal axis substantially greater in length than the horizontal and vertical axes and which is capable of substantial relative elastic deformation in both the vertical and horizontal planes.
These and other advantages, features and objects of the invention will become apparent from the drawings, detailed description and claims which follow.